There are many tubular tissues including blood vessels in a body, and blood vessels, for example, can have disorders such as stenosis, occlusion, aneurysm, and varix. In particular, the aneurysm is a serious disorder that causes massive bleeding when ruptured, for which therefore immediate treatment is necessary. Accordingly, various kinds of instruments have been developed to perform effective treatment.
Recently, a metal cylindrical instrument called stent has been often used in the treatment of a stenosis site or an aneurysm of a blood vessel. In the case of the treatment of a stenosis site, for example, a stent is conveyed to an affected area while being contained in a sheath or a catheter (hereinafter, referred to as sheath) and once the stent reaches the affected area, separated from the sheath, expanded by means of a balloon to expand the stenosis site, and indwelled to treat the stenosis site. In the case of the treatment of an aortic aneurysm, a stent graft obtained by coating a stent with an artificial blood vessel is indwelled inside of the aneurysm and opposed to the pressure of blood thereby to prevent the pressure from acting on the aneurysm for the treatment.
Examples of the stent include the one constituted solely by loop stents each formed into a cylindrical shape as a whole by folding a round bar-shaped wire into a zigzag shape and joining ends of the wire together. Another example of the stent is formed by arranging a plurality of loop stents according to the curvature of the affected area where the stent is to be indwelled, and connecting the loop stents together via a plurality of linear members called struts so as to maintain the shape of the curvature (see, for example, Patent Document 1).
The above-mentioned stents are each conveyed to the affected area while being contracted and inserted in a sheath and once the stent reaches the affected area and then is separated from the sheath, expanded by a balloon or expands by itself. In the stent formed by connecting a plurality of loop stents by struts, in particular, the arrangement of the respective loop stents along the curvature is maintained by the struts, and the loop stents expanded contact with the inner wall surface of the affected area. Thereby, the stent can treat an applicable tubular tissue, for example, a blood vessel.
[Patent Document 1] Japanese Patent No. 4064724